Naval dispatch from the Commander in Chief Pacific (CINCPAC) announcing the Japanese attack on Pearl Harbor

The Japanese Attacked Pearl Harbor
December 7, 1941
"AIR RAID ON PEARL HARBOR X THIS IS NOT DRILL."

The ranking United States naval officer in Pearl Harbor, known as the Commander-in-Chief Pacific, sent this hurried dispatch to all major navy commands and fleet units. Radio stations receiving the news interrupted regular broadcasts to announce the tragic news to the American public. Most people knew what the attack meant for the U.S. even before Roosevelt's official announcement the next day. The U.S. would declare war on Japan.